1. Field of the Invention
The present invention relates to a method and an apparatus for optical distance measurement with respect to specular surfaces.
2. Brief Description of the Prior Art
The customary triangulation theorem for optical distance measurement is based on a measurement of the angular position of a stray light spot, which is produced by a light beam (for example laser) on the surface to be measured. This theorem encounters considerable difficulties in the case of highly reflective surfaces, since they reflect the incident light in accordance with the law of reflection only in one direction and do not scatter it, or only to a slight extent, in the direction of the receiver.